代码:
#include<bits/stdc++.h>
using namespace std;
typedef struct node{
int data;
struct node *lchild,*rchild;
}*BiTree;
void createTree(BiTree &T,int x,int parent)
{
if(T==NULL)
{
T = new node;
T->data=x;
T->lchild=T->rchild=NULL;
cout<<parent<<endl;
return;
}
if(x==T->data) return;
else if(x<T->data) createTree(T->lchild,x,T->data);
else createTree(T->rchild,x,T->data);
}
int main()
{
int n;
while(cin>>n)
{
BiTree T=NULL;
while(n--)
{
int x;
cin>>x;
createTree(T,x,-1);
}
}
return 0;
}